Control device for vehicle drive device

ABSTRACT

A control device of a vehicle drive device including an electromagnetic valve oil pump sucking and discharging hydraulic oil through ON/OFF operations of an electromagnetic valve, a drive frequency controller for controlling a drive frequency at which the electromagnetic valve is to be turned on/off, a temperature sensor for detecting an oil temperature of the hydraulic oil, and a hydraulic circuit supplied with the hydraulic oil discharged from the electromagnetic valve oil pump, the control device of a vehicle drive device further including a surge absorption circuit absorbing a counter electromotive force generated in the electromagnetic valve oil pump, the drive frequency of operation of the electromagnetic valve oil pump being set lower when the oil temperature is low than when the oil temperature is high.

TECHNICAL FIELD

The present invention relates to a control device of a vehicle drive device and particularly to control of a drive device including an electromagnetic valve oil pump.

BACKGROUND ART

An actuator of a vehicle driven by an oil pressure such as a hydraulic clutch is conventionally supplied with hydraulic oil from a mechanical oil pump driven mainly by an engine. It is also proposed to include not only the mechanical oil pump but also an electromagnetic valve oil pump. For example, a pump device described in Patent Document 1 is an example thereof. Patent Document 1 discloses a configuration including an electromagnetic valve oil pump in addition to a mechanical oil pump driven by an engine. For example, when a vehicle is stopped with a shift range maintained in a D-range as in the case of waiting for a traffic light, the engine is automatically stopped and the electromagnetic valve oil pump is driven to supply a proper oil pressure in preparation for the next start so as to enable a prompt start. The electromagnetic valve oil pump of Patent Document 1 has a drive frequency of an electromagnetic valve made variable to enable the supply of the optimum oil pressure regardless of aged deterioration of a vehicle.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Japanese Laid-Open Patent Publication No. 2011-69258

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

The electromagnetic valve oil pump applies a current repeatedly turned on and off to an electromagnetic valve to cause a plunger (piston) disposed in a solenoid coil to reciprocate, thereby repeatedly suck and discharge hydraulic oil. This plunger is coupled to a spring biasing the plunger in one direction and, it is known that when the energization of the electromagnetic valve is switched off and the plunger moves in the solenoid coil due to the spring, a surge power (counter electromotive force) is generated in a drive circuit of the electromagnetic valve. Therefore, a surge absorption circuit absorbing this surge power is typically disposed. When a surge absorption power absorbed by the surge absorption circuit becomes large, a circuit scale increases for ensuring heat resistance, resulting in a larger size and higher cost of the surge absorption circuit. Therefore, it is desired to reduce the surge absorption power.

Since the electromagnetic valve oil pump is connected via a valve body etc. to a hydraulic clutch, leakage of the hydraulic oil occurs from the valve body, for example. A leakage amount of the hydraulic oil changes depending on an oil temperature of the hydraulic oil and, for example, the leakage amount becomes larger at higher oil temperature. Since the design is based on a state at the time of high oil temperature associated with a large leakage amount, the electromagnetic valve oil pump is required to have a larger discharge amount. However, a smaller leakage amount at the time of low oil temperature leads to excessive flow rate and oil pressure, resulting in an energy loss. When the oil temperature of the hydraulic oil is low, the surge absorption power becomes large in association with increased viscous resistance of the hydraulic oil and an increased solenoid current flowing through the solenoid coil. Therefore, a large surge absorption circuit is required. In Patent Document 1, no consideration is given to a change in the viscous resistance due to a change in the oil temperature of the hydraulic oil. Therefore, even if consideration is given to the leakage amount of the hydraulic oil, since the design is based on a state at the time of high oil temperature associated with a large leakage amount and the solenoid current becomes large at the time of low oil temperature and therefore increases the surge power, a large-sized surge absorption circuit is required, resulting in a problem of a higher cost.

The present invention was conceived in view of the situations and it is therefore an object of the present invention to provide a control device of a vehicle drive device including an electromagnetic valve oil pump and capable of reducing a size of a surge absorption circuit absorbing a surge generated during operation of the electromagnetic valve oil pump.

Means for Solving the Problem

To achieve the object, the first aspect of the invention provides a control device of a vehicle drive device including (a) an electromagnetic valve oil pump sucking and discharging hydraulic oil through ON/OFF operations of an electromagnetic valve, a means of controlling a drive frequency at which the electromagnetic valve oil pump is to be turned on/off, a means of detecting an oil temperature of the hydraulic oil, and a hydraulic circuit supplied with the hydraulic oil discharged from the electromagnetic valve oil pump, the control device of a vehicle drive device further including (b) a surge absorption circuit absorbing a counter electromotive force generated in the electromagnetic valve oil pump, (c) the drive frequency of operation of the electromagnetic valve oil pump being set lower when the oil temperature is low than when the oil temperature is high.

Effect of the Invention

For example, if the electromagnetic valve oil pump is operated at a constant drive frequency regardless of an oil temperature and the oil temperature is low, the viscous resistance of the hydraulic oil is large and the solenoid current flowing through the electromagnetic valve oil pump is increased. Therefore, a surge power becomes large and therefore necessitates a surge absorption circuit having a large physical size designed with a large surge absorption power. The leakage amount of the hydraulic oil from the hydraulic circuit becomes smaller as the viscous resistance of the hydraulic oil becomes larger. In other words, the leakage amount of the hydraulic oil from the hydraulic circuit has characteristics that the leakage amount becomes smaller as the oil temperature becomes lower. As a result, when the oil temperature is low, the leakage amount becomes smaller and, therefore, a required flow rate can be ensured even if the discharge flow rate of the electromagnetic valve oil pump is suppressed as compared to when the oil temperature is high. The drive frequency of operation of the electromagnetic valve oil pump is set lower when the oil temperature is low than when the oil temperature is high. This setting makes the drive frequency lower and therefore makes the discharge amount of the electromagnetic valve oil pump smaller when the oil temperature is low; however, since the leakage amount of the hydraulic oil becomes smaller, the required flow rate can be ensured. Since the surge power is proportional to the drive frequency, the surge power becomes small even at the time of low oil temperature and, therefore, the surge absorption circuit can be reduced in size. On the other hand, the leakage amount becomes larger at the time of high oil temperature and, therefore, the drive frequency is made higher to increase the discharge amount of the electromagnetic valve oil pump; however, since the viscous resistance of the hydraulic oil is small at the time of high oil temperature and the solenoid current becomes lower as compared to the time of low temperature, the surge power does not become large. Thus, the surge absorption circuit can be reduced in size.

Preferably, the second aspect of the invention provides the control device of a vehicle drive device recited in the first aspect of the invention, wherein the oil temperature of the hydraulic oil is calculated based on a solenoid current of the electromagnetic valve. As a result, the oil temperature can be detected without using a sensor etc.

Preferably, the third aspect of the invention provides the control device of a vehicle drive device recited in the first aspect of the invention, wherein the drive frequency of the electromagnetic valve oil pump continuously varies depending on the oil temperature. As a result, the frequency is set such that the required flow rate can be ensured depending on the oil temperature, and an extra flow rate and oil pressure can be suppressed to prevent the energy loss.

Preferably, the fourth aspect of the invention provides the control device of a vehicle drive device recited in the first aspect of the invention, wherein the drive frequency of the electromagnetic valve oil pump varies in stages based on a preset threshold value of the oil temperature. As a result, the frequency varies based on the threshold values of the oil temperature and the required flow rate can be ensured while suppressing the surge power.

Preferably, the fifth aspect of the invention provides the control device of a vehicle drive device recited in the first aspect of the invention, wherein the oil temperature of the hydraulic oil is detected by an oil temperature sensor and calculated based on the solenoid current of the electromagnetic valve, wherein the oil temperature is normally detected by the oil temperature sensor, and is calculated based on the solenoid current when the oil temperature is not detected by the oil temperature sensor. As a result, a reliable value of the oil temperature is normally detected by the oil temperature sensor and, even if the oil temperature cannot be detected by the oil temperature sensor, the oil temperature can be calculated based on the solenoid current of the electromagnetic valve, and the optimum drive frequency can be set based on the oil temperature. For example, if the oil temperature is detected only by the oil temperature sensor and the detection by the oil temperature sensor becomes unavailable, the optimum discharge amount of the electromagnetic valve oil pump based on the oil temperature becomes unknown and, therefore, the drive frequency must be made high so as to ensure the discharge amount. Thus, the surge power becomes large, which necessitates corresponding enlargement of the surge absorption circuit. In contrast, since the oil temperature can be calculated based on the solenoid current of the electromagnetic valve, even if the oil temperature cannot be detected by the oil pressure sensor, the oil temperature is calculated based on the solenoid current of the electromagnetic valve so as to set the drive frequency to an optimum value and, therefore, the surge power is suppressed so that the surge absorption circuit is certainly prevented from increasing in size.

Preferably, the sixth aspect of the invention provides the control device of a vehicle drive device recited in the fifth aspect of the invention, wherein a control portion supplied with an oil temperature signal from the oil temperature sensor is separated from a control portion configured to control the oil temperature based on the solenoid current of the electromagnetic valve. As a result, even if a failure or communication abnormality occurs in the oil pressure sensor, the oil temperature can be calculated based on the solenoid current of the electromagnetic valve without being affected and the surge absorption circuit can certainly be prevented from increasing in size.

Preferably, the seventh aspect of the invention provides the control device of a vehicle drive device recited in the first aspect of the invention, wherein a mechanical oil pump driven by an engine is further included, and wherein the electromagnetic valve oil pump is driven during stop of the engine. As a result, although the mechanical oil pump is stopped during stop of the engine, the electromagnetic valve oil pump is driven instead and, therefore, insufficient supply of the hydraulic oil can be avoided.

Preferably, the eighth aspect of the invention provides the control device of a vehicle drive device recited in the seventh aspect of the invention, wherein the hydraulic oil discharged from the electromagnetic valve oil pump is supplied to a start clutch of a transmission. As a result, although the mechanical oil pump is stopped by stopping the engine during stop of the vehicle, since the hydraulic oil is supplied from the electromagnetic valve oil pump to the start clutch of the transmission during this period, the start clutch of the transmission can promptly be engaged to enable a smooth start when the vehicle is restarted.

Preferably, the ninth aspect of the invention provides the control device of a vehicle drive device recited in the first aspect of the invention, wherein the electromagnetic valve oil pump has an intake oil passage for sucking the hydraulic oil and a discharge oil passage for discharging the hydraulic oil, and wherein a cross-sectional area of the intake oil passage is larger than a cross-sectional area of the discharge oil passage. Since this reduces the resistance acting on the hydraulic oil that is being sucked from the intake oil passage, the controllability of the electromagnetic valve oil pump is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for explaining a general configuration of a power transmission path from an engine to drive wheels making up a vehicle drive device to which the present invention is applied, and is a block diagram for explaining a main portion of a control system disposed in the vehicle drive device.

FIG. 2 depicts a part of a hydraulic circuit controlling the vehicle drive device of FIG. 1, particularly a hydraulic circuit controlling the start clutch in a simplified manner.

FIG. 3 is a diagram for explaining structure and operation of the electromagnetic valve oil pump of FIG. 2.

FIG. 4 depicts changes with time in current and voltage when the electromagnetic valve oil pump of FIG. 3 is driven.

FIG. 5 depicts a relationship between oil pressure/oil temperature and a leakage amount of the hydraulic oil.

FIG. 6 is a functional block diagram for mainly explaining a control operation of the electromagnetic valve oil pump in an electronic control device of FIG. 1.

FIG. 7 depicts a map representative of a relationship between a solenoid current and the oil temperature.

FIG. 8 depicts a map representative of a relationship between the oil temperature and a required flow rate.

FIG. 9 is a map determining drive frequency based on the required flow rate.

FIG. 10 depicts changes in voltage and current relative to the drive frequency.

FIG. 11 is a flowchart for explaining the control operation of the electronic control device, particularly the control operation of the electromagnetic valve oil pump.

FIG. 12 depicts a relationship between the oil temperature/the drive frequency and a surge absorption power, the relationship being obtained from another example of the present invention.

FIG. 13 depicts the surge absorption power to the drive frequency on a time axis.

FIG. 14 is a flowchart for explaining the control operation of the electronic control device of a further example of the present invention, i.e., the control operation of the electromagnetic valve oil pump.

MODE FOR CARRYING OUT THE INVENTION

An example of the present invention will now be described in detail with reference to the drawings. In the following example, the figures are simplified or deformed as needed and portions are not necessarily precisely depicted in terms of dimension ratio, shape, etc.

FIRST EXAMPLE

FIG. 1 is a diagram for explaining a general configuration of a power transmission path from an engine 12 to drive wheels 14 making up a vehicle drive device 10 to which the present invention is applied, and is a block diagram for explaining a main portion of a control system disposed in the vehicle drive device 10. In FIG. 1, a transmission mechanism portion 16 is, for example, a stepped automatic transmission or a continuously variable automatic transmission (CVT) transversely mounted on a vehicle and preferably used in an FF (front-engine front-drive) type vehicle and is coupled via a torque converter 17 to the engine 12. Power is input, from the engine 12 that is an internal combustion engine acting as a drive force source for running, through the torque converter 17 to the transmission mechanism portion 16, and is transmitted from an output gear 18 acting as an output rotating member making up one gear of a counter gear pair 20, sequentially via the counter gear pair 20, a final gear pair 22, a differential gear device (differential gear) 24, a pair of axles (drive shafts (D/S)) 26, etc. acting as a power transmission device, to a pair of the drive wheels 14. A transaxle (T/A) is made up of the transmission mechanism portion 16, the counter gear pair 20, the final gear pair 22, the differential gear device (differential gear) 24, etc.

The engine 12 is, for example, an internal combustion engine such as a gasoline engine and a diesel engine, and includes an electronic throttle valve 54 disposed in an intake pipe 50 and driven to open/close by a throttle actuator 52, a fuel injection device 56 injecting fuel into a cylinder, and an ignition device 58 igniting the injected fuel.

A wheel brake device 64 is a well-known drum brake or disk brake and is disposed for each of wheels (wheels including the drive wheels 14 as well as driven wheels) to brake the wheels in accordance with a depression operation of a foot brake pedal 66. In other words, the wheel brake device 64 brakes the wheels in accordance with a brake oil pressure generated by the depression operation of the foot brake pedal 66.

The vehicle drive device 10 includes an electronic control device 80 having a function as a vehicle engine control device controlling the engine 12. The electronic control device 80 includes, for example, a so-called microcomputer including a CPU, a RAM, a ROM, an input/output interface, etc., and executes signal processes in accordance with a program stored in advance in the ROM, while utilizing a temporary storage function of the RAM, to provide the output control of the engine 12, the shift control of the transmission mechanism portion 16, and the drive control of an electromagnetic valve oil pump 86 described later. The electronic control device 80 is made up of a plurality of control devices such as an E/G-ECU exclusively executing the output control of the engine 12, an A/T-ECU exclusively executing the shift control of the transmission mechanism portion 16, and an O/P-ECU exclusively executing the drive control of the electromagnetic valve oil pump 86, and data are transferred among these control devices to each other through communication.

The electronic control device 80 is supplied with, for example, an engine rotation speed signal corresponding to a crank angle (position) Acr of a crankshaft and an engine rotation speed Ne of the engine 12 from an engine rotation speed sensor 28, an input rotation speed signal corresponding to a rotation speed Nin of an input shaft of the transmission mechanism portion 16 from an input rotation speed sensor 30, a vehicle speed signal indicative of a vehicle speed V corresponding to a rotation speed Nout of the output gear 18 from a vehicle speed sensor 32, wheel speed signals corresponding to rotation speeds Nw of the wheels from wheel speed sensors 34, a signal indicative of the presence of operation of an accelerator pedal 68 and an operation amount (accelerator opening degree Acc) of the accelerator pedal 68 from an accelerator opening degree sensor 36, a signal from a footbrake switch 38 indicative of the presence of a brake operation for causing the wheel brake device 64 to brake the wheels, i.e., the presence of the depression operation of the brake pedal 66, and a signal indicative of an oil temperature Toil of hydraulic oil from an oil temperature sensor 40.

The electronic control device 80 outputs, for example, engine output control command signals for the output control of the engine 12, for example, a drive signal to the throttle actuator 52 establishing an opening degree θth (throttle valve opening degree θth) of the electronic throttle valve 54, a fuel supply amount signal controlling an amount of fuel supply into each cylinder of the engine 12 by the fuel injection device 56, and an ignition signal commanding the timing of ignition of the engine 12 by the ignition device 58; a shift control command signal for the shift control of the transmission mechanism portion 16; and a drive signal driving the electromagnetic valve oil pump 86. For example, the electronic control device 80 outputs the shift control command signal to a hydraulic control circuit (not depicted) based on the input rotation speed signal, an output rotation speed signal, etc., so as to provide the switching control of the gear ratio of the transmission mechanism portion 16. Basically, the electronic control device 80 drives the throttle actuator 52 based on the accelerator opening degree Acc from a relationship (not depicted) stored in advance, as part of the output control of the engine 12, so as to provide throttle control such that the throttle valve opening degree θth is increased with an increase in the accelerator opening degree Acc. When the engine 12 is stopped, the electronic control device 80 provides control of driving the electromagnetic valve oil pump 86.

The electronic control device 80 of this example provides so-called idling reduction control of temporarily automatically stopping the engine 12 in association with a stop of running of the vehicle for fuel efficiency improvement. For example, in such a case that the vehicle waits for a traffic light, the vehicle is stopped while a shift range is a D-range with the brake pedal 66 depressed, and the engine 12 is temporarily automatically stopped in this case. Since the temporary stop of the engine 12 in the idling reduction control means that the fuel supply to the engine is stopped to put the engine 12 into a non-drive state and the engine rotation speed Ne is not limited to zero in the non-drive state, the temporary stop of the engine 12 includes the case that the engine rotation speed Ne is not zero. The fuel efficiency in this example refers to a running distance per unit fuel consumption etc., and an improvement in fuel efficiency refers to extension of the running distance per unit fuel consumption, or a reduction in fuel consumption rate (=fuel consumption/drive wheel output) of the vehicle as a whole. Contrarily, a reduction (deterioration) in fuel efficiency refers to shortening of the running distance per unit fuel consumption or an increase in fuel consumption rate of the vehicle as a whole.

When the accelerator pedal 68 is depressed in the state of the idle reduction control, a prompt start of the vehicle is desirable. However, since the engine 12 is stopped during the idle reduction control, a mechanical oil pump driven by the engine 12 is also stopped. Therefore, a delay may occur in engagement of a start clutch C1 of the transmission mechanism portion 16 engaged at the start of the vehicle, and the start responsiveness of the vehicle may deteriorate. In this regard, the vehicle of this example drives the electromagnetic valve oil pump 86 described later instead of the mechanical pump during the idle reduction control (during engine stop) to supply the hydraulic oil to the start clutch C1 in advance so that a state immediately before engagement is achieved, thereby enabling a prompt start.

FIG. 2 depicts a hydraulic circuit 82 controlling the start clutch C1 in a simplified manner. As depicted in FIG. 2, the hydraulic control circuit 82 has two oil pumps, which are a mechanical oil pump 84 driven by the engine 12 and the electromagnetic valve oil pump 86 including an electromagnetic valve 104 and driven by the electromagnetic valve 104, and the hydraulic oil discharged from these oil pumps is selectively supplied via a switching valve 93 to the start clutch C1.

The mechanical oil pump 84 is driven when the engine 12 is driven, and pumps up the hydraulic oil stored in an oil pan 88 to discharge the hydraulic oil toward a pressure adjusting circuit 90. The pressure adjusting circuit 90 includes, for example, a regulator valve (not depicted) and uses the hydraulic oil discharged from the mechanical oil pump 84 as an original pressure to adjust an optimum line pressure depending on a running state of the vehicle. A solenoid valve SL1 uses the line pressure as an original pressure to adjust the line pressure to an optimum clutch pressure Pc1 depending on the running state of the vehicle. This adjusted clutch pressure Pc1 is supplied via the switching valve 93 to the start clutch C1.

The electromagnetic valve oil pump 86 pumps up the hydraulic oil stored in the oil pan 88 to supply the hydraulic oil via the switching valve 93 to the start clutch C1. The switching valve 93 is a switching valve switching between the solenoid valve SL1 and the electromagnetic valve oil pump 86, through which the hydraulic oil is to be supplied to the start clutch C1. If the mechanical oil pump 84 is operated, the switching valve 93 allows the communication between the solenoid valve SL1 and the start clutch C1 and interrupts the communication between the electromagnetic valve oil pump 86 and the start clutch C1. If the mechanical oil pump 86 is not driven, the switching valve 93 allows the communication between the electromagnetic valve oil pump 86 and the start clutch C1 and interrupts the communication between the solenoid valve SL1 and the start clutch C1. Specific structure and operation of the switching valve 93 are known techniques and therefore will not be described. The hydraulic oil discharged from the electromagnetic valve oil pump 86 is directly supplied via the switching valve 93 to the start clutch C1, without the supplied hydraulic oil being adjusted. Therefore, the electromagnetic valve oil pump 86 is an oil pump supplying the hydraulic oil to the start clutch C1 exclusively during the idle reduction control.

FIG. 3 depicts structure of the electromagnetic valve oil pump 86. FIG. 3( a) depicts a state of sucking the hydraulic oil from the oil pan 88 and FIG. 3( b) depicts a state of discharging the hydraulic oil toward the start clutch C1. The electromagnetic valve oil pump 86 includes a column-shaped plunger 94 reciprocating in a cylindrical case 92, a solenoid coil 96 (electromagnetic portion) repeating ON/OFF operations at a predetermined duty ratio and drive frequency F for reciprocating the plunger 94, a spring 98 biasing the plunger 94 toward the side on which the hydraulic oil is discharged (the right side of FIG. 3), an intake oil passage 99 connecting the oil pan 88 and the electromagnetic valve oil pump 86 for sucking the hydraulic oil, a discharge oil passage 100 connecting the electromagnetic valve oil pump 86 and the switching valve 93 (start clutch C1) for discharging the hydraulic oil, a first check valve 101 preventing a backward flow of the hydraulic oil sucked from the oil pan 88, and a second check valve 102 preventing a backward flow of the hydraulic oil discharged from the electromagnetic valve oil pump 86. By creating an energized state in which a solenoid current is applied to the solenoid coil 96 and a non-energized state in which the solenoid current is not applied and repeating the ON/OFF operations between the energized state and the non-energized state at a predetermined drive frequency, the hydraulic oil is repeatedly sucked and discharged in the electromagnetic valve oil pump 86. The electromagnetic valve oil pump 86 has the electromagnetic valve 104 made up of the case 92, the plunger 94, the solenoid coil 96, and spring 98.

As depicted in FIG. 3( a), when the solenoid coil 96 is energized and the plunger 94 moves toward the spring 98 (the left side of FIG. 3), since a differential pressure acts between opposite sides of the first check valve 101, the first check valve 101 is opened by the differential pressure and the hydraulic oil is sucked into the case 92 from the intake oil passage 99 connected to the oil pan 88. In this case, the second check valve 102 is closed. As depicted in FIG. 3( b), when the non-energized state is established, the plunger 94 is moved by the biasing force of the spring 98 toward the check valve (the right side of FIG. 3) and the hydraulic oil is discharged through the second check valve 102 toward the discharge oil passage 100 connected to the start clutch C1. In this case, the first check valve 101 is closed. Since the plunger 94 reciprocates in the case 92, the hydraulic oil of the oil pan 88 is sucked through the intake oil passage 99 and the sucked hydraulic oil is discharged toward the discharge oil passage 100. A cross-sectional area Ain of the intake oil passage 99 for sucking the hydraulic oil is made larger than a cross-sectional area Aout of the discharge oil passage 100 for discharging the hydraulic oil. Since this reduces the resistance acting on the hydraulic oil that is being sucked into the electromagnetic valve oil pump 86, the controllability of the electromagnetic valve oil pump 86 is improved.

The electromagnetic valve oil pump 86 of this example includes a drive frequency switching circuit 108 switching the drive frequency F, and the discharge amount of the electromagnetic valve oil pump 86 can be adjusted by switching the drive frequency F. When the plunger 94 is moved by the biasing force of the spring 98 in the solenoid coil 96 as depicted in FIG. 3( b), a surge power (counter electromotive force) is generated in the circuit. FIG. 4 depicts changes with time in current I and voltage V when the electromagnetic valve oil pump 86 is driven. In FIG. 4, a solid line indicates the voltage V and a broken line indicates the current I. When the solenoid coil 96 is energized, the voltage has a positive value. When the solenoid coil 96 is switched to be non-energized, the counter electromotive force (surge power) is generated as a negative value as the plunger 94 moves in the solenoid coil 96. Although the drive frequency switching circuit 108 of this example has the O/P-ECU controlling the electromagnetic valve oil pump 86 incorporated in the drive frequency switching circuit 108 as depicted in FIG. 2, the O/P-ECU may be disposed separately from the drive frequency switching circuit 108.

Therefore, a surge absorption circuit 110 for absorbing this surge power is interposed between the solenoid coil 96 of the electromagnetic valve oil pump 86 and the drive frequency switching circuit 108. The surge absorption circuit 110 includes a rectifier diode 112 and a Zener diode 114, for example. A surge absorption power W absorbed by the surge absorption circuit 110 is calculated by following Equation (1). In Equation (1), I denotes a solenoid current [A]; Vz denotes a Zener voltage [V]; t denotes a surge width [s] depicted in FIG. 4; and F denotes a drive frequency [Hz]. The Zener voltage Vz is a rated value determined based on the Zener diode 114.

W=I×V _(z) ×t×F   (1)

When the surge absorption power W becomes larger, a circuit scale of the surge absorption circuit 110 increases for ensuring heat resistance and costs become higher. Therefore, it is desirable to reduce the surge absorption power W.

A hydraulic circuit (corresponding to a hydraulic circuit of the present invention) including the discharge oil passage 100 and the switching valve 93 and connecting the electromagnetic valve oil pump 86 and the start clutch C1 is formed in a valve body (not depicted), and leakage of the hydraulic oil occurs when the hydraulic oil passes through the valve body. FIG. 5 depicts a relationship between oil pressure/oil temperature and a leakage amount of the hydraulic oil. As depicted in FIG. 5, the leakage amount of the hydraulic oil increases as the oil pressure becomes higher. The leakage amount becomes large when the hydraulic oil is at high oil temperature as compared to the case of low oil temperature. This is because the viscous resistance of the hydraulic oil decreases as the oil temperature Toil of hydraulic oil becomes higher. Therefore, since the leakage amount is reduced at the time of low oil temperature, the hydraulic oil required for the start clutch C1 can be supplied even if the discharge amount from the electromagnetic valve oil pump 86 is reduced as compared to the time of high oil temperature. However, the discharge amount of the electromagnetic valve oil pump 86 is conventionally not variable and the discharge amount of the electromagnetic valve oil pump 86 is designed based on a state of a large leakage amount (the time of high oil temperature). Therefore, the flow rate and oil pressure of the hydraulic oil become excessive at the time of low oil temperature, resulting in an energy loss and deteriorating the fuel efficiency, and the clutch oil pressure of the start clutch C1 may become excessive, resulting in a torque transmission shock. To increase the flow rate of the hydraulic oil, the drive frequency F of the electromagnetic valve oil pump 86 is set to a higher value, and the surge absorption power W becomes larger in relation to this setting as can be seen from Equation (1). Therefore, the surge absorption circuit 110 increases in size for ensuring the heat resistance for the surge absorption power W, resulting in a cost increase.

When the electromagnetic valve oil pump 86 is driven in this example, the drive frequency F of the electromagnetic valve oil pump 86 is changed depending on the oil temperature Toil of the hydraulic oil to optimally control the discharge flow amount from the electromagnetic valve oil pump 86, thereby suppressing the surge absorption power W and preventing the surge absorption circuit 110 from increasing in size. Specifically, the drive frequency F is set lower in the case of low temperature as compared to the case of high temperature, thereby suppressing the surge absorption power W and preventing the surge absorption circuit 110 from increasing in size. A main portion of the present invention, i.e., the drive control of the electromagnetic valve oil pump 86 will hereinafter be described.

FIG. 6 is a functional block diagram for mainly explaining a control operation of the electromagnetic valve oil pump 86 in the electronic control device 80. Although the O/P-ECU is incorporated in the drive frequency switching circuit 108 in the block diagram of FIG. 2, the O/P-ECU is depicted separately from the drive frequency switching circuit 108 in the functional block diagram of FIG. 6 so as to describe specific functions of the O/P-ECU.

An oil temperature detecting portion 130 (an oil temperature detecting means) depicted in FIG. 6 detects the oil temperature Toil of the hydraulic oil flowing through the hydraulic circuit 82. The oil temperature detecting portion 130 detects the oil temperature Toil from the oil temperature sensor 40 disposed in the oil pan 88 storing the hydraulic oil. Alternatively, the oil temperature detecting portion 130 detects the solenoid current I [A] of the electromagnetic valve 104 (the electromagnetic valve oil pump 86) from the drive frequency switching circuit 108 and calculates the oil temperature Toil based on the solenoid current I. FIG. 7 depicts a map which is representative of a relationship between the solenoid current I and the oil temperature Toil, and which is obtained from an experiment or analysis in advance. As depicted in FIG. 7, as the oil temperature Toil decreases, the viscous resistance of the hydraulic oil increases and the solenoid current I increases. The oil temperature detecting portion 130 detects the solenoid current I and determines the oil temperature Toil based on the map of FIG. 7 obtained and stored in advance. The oil temperature Toil may be calculated based on not only the map depicted in FIG. 7 but also an empirical formula empirically obtained in advance for calculating the oil temperature Toil.

A required flow rate calculating portion 132 (a required flow rate calculating means) calculates a required flow rate Q [cc/min] required for the electromagnetic valve oil pump 86 based on the oil temperature Toil obtained by the oil temperature detecting portion 130. The required flow rate Q is a flow rate of the hydraulic oil required for the start clutch C1. FIG. 8 depicts a map representative of a relationship between the oil temperature Toil and the required flow rate Q obtained from an experiment or analysis in advance. As depicted in FIG. 8, the required flow rate Q increases as the oil temperature Toil becomes higher. This is because a higher oil temperature Toil reduces the viscosity of the hydraulic oil and increases the leakage from the hydraulic circuit and the required flow rate Q is increased by an amount of the leakage. The required flow rate calculating portion 132 determines the required flow rate Q from the calculated oil temperature Toil based on the map depicted in FIG. 8 obtained and stored in advance. The required flow rate Q may be calculated based on not only the map depicted in FIG. 8 but also an empirical formula empirically obtained in advance for calculating the required flow rate Q.

A drive frequency calculating portion 134 (a drive frequency calculating means) determines the drive frequency F [Hz] of the electromagnetic valve oil pump 86 based on the required flow rate Q obtained by the required flow rate calculating portion 132. FIG. 9 is a map determining the drive frequency F based on the required flow rate Q. FIG. 9 is obtained empirically or analytically in advance such that the drive frequency F satisfying the required flow rate Q is set. As depicted in FIG. 9, the drive frequency F increases as the required flow rate Q increases. As a result, the drive frequency F of the electromagnetic valve oil pump 86 continuously varies depending on the oil temperature Toil.

A drive frequency changing portion 136 outputs, to the drive frequency switching circuit 108, a command for driving the electromagnetic valve oil pump 86 such that the electromagnetic valve 104 is turned on and off at the drive frequency F obtained by the drive frequency calculating portion 134. When this control is provided, the drive frequency F becomes lower in the case of low oil temperature as compared to the case of high oil temperature in accordance with the maps of FIGS. 7 to 9. FIG. 10 depicts changes in voltage and current relative to the drive frequency F. FIG. 10( a) represents the time of high oil temperature, i.e., a state when the drive frequency F is high, and FIG. 10( b) represents a state at the time of low oil temperature, i.e., a state when the drive frequency F is low. In FIG. 10, a solid line indicates a voltage [V] and a broken line indicates a current I [A]. As depicted in FIG. 10, since the drive frequency F becomes lower at the time of low oil temperature of FIG. 10( b), the number of times of occurrence of the surge power becomes lower as compared to the time of high oil temperature of FIG. 10( a) and, therefore, the surge absorption power W is reduced. When the drive frequency F becomes lower at the time of low oil temperature, the discharge amount discharged from the electromagnetic valve oil pump 86 decreases; however, since the leakage amount of the hydraulic oil becomes smaller at the time of low oil temperature as described above, the required flow rate Q also becomes smaller. Therefore, even if the drive frequency F becomes lower and the discharge amount of the hydraulic oil from the electromagnetic valve oil pump 86 becomes smaller, the required flow rate Q is ensured. On the other hand, although the leakage amount becomes larger and the required flow rate Q becomes larger at the time of high oil temperature, the required flow rate Q is satisfied since the drive frequency F becomes higher. Although the drive frequency F becomes higher at the time of high oil temperature, the solenoid current I is lower at the time of high oil temperature as compared to the time of low oil temperature as can be seen from FIG. 10( a) and, therefore, an increase in the surge absorption power W is suppressed. Therefore, since the maximum value of the surge absorption power W of the surge absorption circuit 110 is made smaller even at the time of low oil temperature, the surge absorption circuit 110 can be reduced in size and cost.

FIG. 11 is a flowchart for explaining a main portion of the control operation of the electronic control device 80, particularly the control operation of the electromagnetic valve oil pump 86, and is repeatedly executed with an extremely short cycle time, for example, on the order of few msec to a few tens of msec.

In FIG. 11, first, at step S1 (hereinafter, step will be omitted) corresponding to the oil temperature detecting portion 130, the solenoid current I of the electromagnetic valve oil pump 86 is input that is relevant to the oil temperature Toil of the hydraulic oil. At step S2 also corresponding to the oil temperature detecting portion 130, the oil temperature Toil of the hydraulic oil is calculated by reference to the solenoid current I input at S1 from the map depicted in FIG. 7 obtained and stored in advance. Although the oil temperature Toil is calculated based on the solenoid current I in the above description, the oil temperature Toil can directly be detected by the oil temperature sensor 40. At S3 corresponding to the required flow rate calculating portion 132, the required flow rate Q is calculated by reference to the oil temperature Toil calculated at S2 from the map depicted in FIG. 8 obtained and stored in advance. At S4 corresponding to the drive frequency calculating portion 134, the drive frequency F is calculated by reference to the required flow rate Q calculated at S3 from the map depicted in FIG. 9 obtained and stored in advance. At S5 corresponding to the drive frequency changing portion 136, a command for operating the electromagnetic valve oil pump 86 at the drive frequency F calculated at S4 is output to the drive frequency switching circuit 108.

As described above, according to this example, the drive frequency F of operation of the electromagnetic valve oil pump 86 is set lower when the oil temperature Toil is low than when the oil temperature Toil is high. This setting makes the drive frequency F lower and therefore makes the discharge amount of the electromagnetic valve oil pump 86 smaller when the oil temperature Toil is low; however, since the leakage amount of the hydraulic oil becomes smaller, the required flow rate can be ensured. Since the surge absorption power W is proportional to the drive frequency F, the surge absorption power W becomes small even at the time of low oil temperature and, therefore, the surge absorption circuit 110 can be reduced in size. On the other hand, the leakage amount becomes larger at the time of high oil temperature and, therefore, the drive frequency F is made higher to increase the discharge amount of the electromagnetic valve oil pump 86; however, since the viscous resistance of the hydraulic oil is small at the time of high oil temperature and the solenoid current I becomes lower as compared to the time of low temperature, the surge absorption power W does not become large. Thus, the surge absorption circuit 110 can be reduced in size. Since the drive frequency F becomes lower at the time of low oil temperature, extra hydraulic oil is not discharged at the time of low oil temperature, and fuel efficiency deterioration and a transmission shock due to excessive toque of the start clutch C1 are prevented.

According to this example, the oil temperature Toil of the hydraulic oil is calculated based on the solenoid current I of the electromagnetic valve. As a result, the oil temperature can be detected without using a sensor etc.

According to this example, the drive frequency F of the electromagnetic valve oil pump 86 continuously varies depending on the oil temperature Toil. As a result, the drive frequency F is set such that the required flow rate can be ensured depending on the oil temperature Toil, and an extra flow rate and oil pressure can be suppressed to prevent the energy loss.

According to this example, the mechanical oil pump 84 driven by the engine 12 is further included and the electromagnetic valve oil pump 86 is driven during stop of the engine 12. As a result, although the mechanical oil pump 84 is stopped during stop of the engine, the electromagnetic valve oil pump 86 is driven instead and, therefore, insufficient supply of the hydraulic oil to the start clutch C1 can be avoided.

According to this example, the hydraulic oil discharged from the electromagnetic valve oil pump 86 is supplied to the start clutch C1 of the transmission mechanism portion 16. As a result, although the mechanical oil pump 84 is stopped by stopping the engine 12 during stop of the vehicle, since the hydraulic oil is supplied from the electromagnetic valve oil pump 86 to the start clutch C1 of the transmission mechanism portion 16 during this period, the start clutch C1 of the transmission mechanism portion 16 can promptly be engaged to enable a smooth start when the vehicle is restarted.

Another example of the present invention will be described. In the following description, the portions common to the examples are denoted by the same reference numerals and will not be described.

SECOND EXAMPLE

Although the drive frequency F of the electromagnetic valve oil pump 86 is continuously changed in the example described above, the drive frequency F may be changed in stages (stepwise). FIG. 12 depicts a relationship between the oil temperature Toil/the drive frequency F and the surge absorption power W. FIG. 12 depicts data of four drive frequencies F of 10 Hz indicated by white squares, 15 Hz indicated by white circles, 20 Hz indicated by black triangles, and 25 Hz indicated by black diamonds. As can be seen from FIG. 12, the surge absorption power W decreases as the oil temperature Toil becomes higher at all the drive frequencies F. At the same oil temperature Toil, the surge absorption power W is more increased when the drive frequency F is higher.

A thick solid line depicted in FIG. 12 indicates the drive frequency F switched depending on the oil temperature Toil. In FIG. 12, the drive frequency F is switched to 10 Hz in a region of the oil temperature Toil less than 50° C.; the drive frequency F is switched to 15 Hz in a region of the oil temperature Toil from 50° C. to 80° C.; the drive frequency F is switched to 20 Hz in a region of the oil temperature Toil from 80° C. to 110° C.; and the drive frequency F is switched to 25 Hz in a region of the oil temperature Toil equal to or greater than 110° C. Therefore, the drive frequency F is set to vary in stages based on threshold values of the oil temperature Toil.

In this example, a value (about 2.7 W) indicated by a dashed-dotted line depicted in FIG. 12 is a maximum value Wmax of the surge absorption power W. The drive frequency F is switched depending on the oil temperature Toil such that the surge absorption power W does not exceed the maximum value Wmax. The required flow rate Q is conventionally set based on a state at the time of high oil temperature associated with a large leakage amount of the hydraulic oil without switching the drive frequency F, and the drive frequency F is set to a high value so as to satisfy the required flow rate Q. Therefore, the maximum value of the surge absorption power W becomes large and the surge absorption circuit 110 is enlarged. For example, the conventional maximum value of the surge absorption power W is set to about 3.6 W (a value at low oil temperature based on the drive frequency of 25 Hz) in FIG. 12. On the other hand, the maximum value of the surge absorption power W is about 2.7 W in this example and, therefore, the maximum value of the surge absorption power W is reduced by a difference ΔW close to about 1 W. Therefore, the surge absorption circuit 110 can be reduced in size.

FIG. 13 depicts the surge absorption power W to the drive frequency F on a time axis. While the drive frequency F is 25 Hz, the surge absorption power W is high and, as the drive frequency F is switched to a lower value, the surge absorption power W is changed stepwise to a lower value. As depicted in FIG. 12, since the drive frequency F is switched to 25 Hz at high temperature, the solenoid current I becomes low and, therefore, the surge absorption power W does not become large. Thus, the surge absorption circuit 110 can be reduced in size.

As described above, according to this example, substantially the same effect as the above-described example is acquired and, since the drive frequency F of the electromagnetic valve oil pump 86 varies in stages based on preset threshold values of the oil temperature Toil, the drive frequency F varies based on the threshold values of the oil temperature Toil and the required flow rate can be ensured while suppressing the surge absorption power W.

THIRD EXAMPLE

Although the oil temperature detecting portion 130 detects the oil temperature Toil through direct detection by the oil temperature sensor 40 or indirect calculation from the solenoid current I relevant to the oil temperature Toil in the above-described examples, the both oil temperature detections are used and the oil temperature Toil is detected by a selected one of the detections in this example.

The oil temperature detecting portion 130 of this example includes both the oil temperature detection by the oil temperature sensor 40 and the oil temperature detection from calculation based on the solenoid current I, and the oil temperature Toil is normally directly detected by the oil temperature sensor 40. The oil temperature detection by the oil temperature sensor 40 is direct oil temperature detection and is therefore more accurate as compared to the case of indirect detection based on the solenoid current I. Therefore, the oil temperature Toil is normally detected by the oil temperature sensor 40.

If the oil temperature detection by the oil temperature sensor 40 becomes difficult because of a failure of the oil pressure sensor 40 etc., the oil temperature Toil is undetectable in a configuration unable to detect an oil temperature based on the solenoid current I and, therefore, the pump is driven at a high drive frequency F so as to avoid an insufficient required flow rate Q, resulting in a larger surge absorption power W and leading to an increase in size of the surge absorption circuit. Alternatively, the idle reduction control is terminated to constantly drive the engine 12, resulting in deterioration in fuel efficiency. In contrast, the oil temperature detecting portion 130 of this example determines whether the oil temperature detection by the oil temperature sensor 40 is available and, if the oil temperature detection by the oil temperature sensor 40 becomes unavailable, a switchover is performed to select the method of detecting the oil temperature Toil from the solenoid current I so as to enable the oil temperature detection even when the oil temperature detection by the oil temperature sensor 40 is impossible, thereby certainly preventing the increase in size of the surge absorption circuit 110 and the termination of the idle reduction control.

As depicted in the functional block diagram of FIG. 6, the oil temperature signal output from the oil temperature sensor 40 is input to the A/T-ECU and the oil temperature signal is transmitted from the A/T-ECU to the O/P-ECU. Therefore, the A/T-ECU supplied with the oil temperature signal from the oil temperature sensor 40 is separated from the O/P-ECU configured to control the oil temperature Toil based on the solenoid current I. Because of this configuration, even if the oil temperature sensor 40 has a failure or a communication abnormality occurs between the A/T-ECU and the O/P-ECU, the oil temperature Toil can be detected by detecting the solenoid current I in the O/P-ECU. The A/T-ECU corresponds to a control portion supplied with the oil temperature signal from the oil temperature sensor, and the O/P-ECU corresponds to a control portion configured to control the oil temperature based on the solenoid current.

FIG. 14 is a flowchart for explaining the control operation of the electronic control device 80 of this example, i.e., the control operation of the electromagnetic valve oil pump 86. First, at step S10 (hereinafter, step will be omitted) corresponding to the oil temperature detecting portion 130, it is determined whether the detection by the oil temperature sensor 40 is available. If it is determined that the oil temperature detection by the oil temperature sensor 40 is not available because of a failure of the oil temperature sensor 40 or a communication abnormality between the A/T-ECU and the O/P-ECU, S10 is negative and the operation goes to S1 corresponding to the oil temperature detecting portion 130. At S1, the solenoid current I is input that is a parameter related to the oil temperature Toil, and at S2 corresponding to the oil temperature detecting portion 130, the oil temperature Toil is calculated based on the solenoid current I obtained at S1. On the other hand, if S10 is affirmative, the operation goes to S12 corresponding to the oil temperature detecting portion 130, and the oil temperature Toil is detected by the oil temperature sensor 40. When the oil temperature Toil is detected, the required flow rate Q is calculated based on the oil temperature Toil at S3 corresponding to the required flow rate calculating portion 132. At S4 corresponding to the drive frequency calculating portion 134, the drive frequency F is calculated based on the required flow rate Q obtained at S3, and the command for operating the electromagnetic valve oil pump 86 at the drive frequency F calculated at S4 is output to the drive frequency switching circuit 108 at S5 corresponding to the drive frequency changing portion 136.

In this way, since the oil temperature detecting portion 130 of this example detects the oil temperature Toil by normally the oil temperature sensor 40, and calculates the oil temperature Toil based on the solenoid current I if the detection of the oil temperature Toil by the oil temperature sensor 40 is difficult, the oil temperature Toil can certainly be detected by calculating the oil temperature Toil based on the solenoid current I so as to avoid the increase in size of the surge absorption circuit 110 and the termination of the idle reduction control.

As described above, according to this example, the oil temperature Toil of the hydraulic oil is detected by the oil temperature sensor 40 and calculated based on the solenoid current I of the electromagnetic valve, and the oil temperature Toil is normally detected by the oil temperature sensor 40, while the oil temperature Toil is calculated based on the solenoid current I when the oil temperature Toil is not detected by the oil temperature sensor 40. As a result, a reliable value of the oil temperature Toil is normally detected by the oil temperature sensor 40 and, even if the oil temperature Toil cannot be detected by the oil temperature sensor 40, the oil temperature Toil can be calculated based on the solenoid current I of the electromagnetic valve, and the optimum drive frequency F can be set based on the oil temperature Toil. For example, if the oil temperature Toil is detected only by the oil temperature sensor 40 and the detection by the oil temperature sensor 40 becomes unavailable, the optimum discharge amount of the electromagnetic valve oil pump 86 based on the oil temperature Toil becomes unknown and, therefore, the drive frequency F must be made high so as to ensure the discharge amount. Thus, the surge absorption power W becomes large, which necessitates corresponding enlargement of the surge absorption circuit 110. In contrast, since the oil temperature Toil can be calculated based on the solenoid current I of the electromagnetic valve in this example, even if the oil temperature Toil cannot be detected by the oil pressure sensor 40, the oil temperature Toil is calculated based on the solenoid current I of the electromagnetic valve so as to set the drive frequency F to an optimum value and, therefore, the surge absorption power is suppressed so that the surge absorption circuit 110 is certainly prevented from increasing in size.

According to this example, the A/T-ECU supplied with the oil temperature signal from the oil temperature sensor 40 is separated from the O/P-ECU configured to control the oil temperature based on the solenoid current I of the electromagnetic valve. As a result, even if a failure or communication abnormality occurs in the oil pressure sensor 40, the oil temperature Toil can be calculated based on the solenoid current I of the electromagnetic valve without being affected and the surge absorption circuit 110 can certainly be prevented from increasing in size.

Although the examples of the present invention have been described in detail with reference to the drawings, the present invention is applied also in other forms.

For example, the examples described above may not necessarily independently be implemented and may be implemented in combination as needed without contradiction.

Although the hydraulic oil discharged from the electromagnetic valve oil pump 86 is supplied to the start clutch C1 of the transmission mechanism portion 16 in the examples, the start clutch C1 is not a limitation and the hydraulic oil may be supplied to any actuator driven by an oil pressure without particular limitation. Although the hydraulic oil discharged from the electromagnetic valve oil pump 86 is supplied only to the start clutch C1 in the examples, the hydraulic oil may selectively be supplied via a switching valve etc. to another actuator.

Although a method of directly detecting the oil temperature Toil from the oil temperature sensor 40 or a method of calculating the oil temperature Toil based on the solenoid current I is applied in the examples, the oil temperature Toil may be detected by either one of the methods. Although the solenoid current I is applied as a parameter related to the oil temperature Toil, any parameter such as an engine water temperature may be employed as needed as long as the oil temperature Toil can indirectly be estimated from the employed parameter.

Although the surge absorption circuit 110 is made up of one rectifier diode and two Zener diodes coupled in series in the examples, this configuration is an example and may be changed as needed without contradiction. Since the maximum value of the surge absorption power W is reduced in the present invention, the surge absorption circuit 110 is accordingly designed to be small.

In the examples, the specific configuration of the electromagnetic valve oil pump 86 is an example and any configuration is applicable as needed as long as the applied configuration enables the discharge amount to be variable by changing the drive frequency F of the electromagnetic valve.

Although the relation maps depicted in FIGS. 7 to 9 are stored in the O/P-ECU in the examples, this is not necessarily a limitation and the relation maps may be stored in another storage device.

The above description is merely an embodiment and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

NOMENCLATURE OF ELEMENTS

10: vehicle drive device

12: engine

16: transmission mechanical portion (transmission)

40: oil temperature sensor

80: electronic control device (control device)

84: mechanical oil pump

86: electromagnetic valve oil pump

99: intake oil passage

100: discharge oil passage

104: electromagnetic valve

110: surge absorption circuit

130: oil temperature detecting portion (means of detecting an oil temperature)

136: drive frequency changing portion (means of controlling a drive frequency)

C1: start clutch

A/T-ECU: control portion supplied with an oil temperature signal from an oil temperature sensor

O/P-ECU: control portion configured to control an oil temperature based on a solenoid current of an electromagnetic valve 

1. A control device of a vehicle drive device including an electromagnetic valve oil pump sucking and discharging hydraulic oil through ON/OFF operations of an electromagnetic valve, a drive frequency controller for controlling a drive frequency at which the electromagnetic valve is to be turned on/off, a temperature sensor for detecting an oil temperature of the hydraulic oil, and a hydraulic circuit supplied with the hydraulic oil discharged from the electromagnetic valve oil pump, the control device of a vehicle drive device further including a surge absorption circuit absorbing a counter electromotive force generated in the electromagnetic valve oil pump, the drive frequency of operation of the electromagnetic valve oil pump being set lower when the oil temperature is low than when the oil temperature is high.
 2. The control device of a vehicle drive device of claim 1, wherein the oil temperature of the hydraulic oil is calculated based on a solenoid current of the electromagnetic valve.
 3. The control device of a vehicle drive device of claim 1, wherein the drive frequency of the electromagnetic valve oil pump continuously varies depending on the oil temperature.
 4. The control device of a vehicle drive device of claim 1, wherein the drive frequency of the electromagnetic valve oil pump varies in stages based on a preset threshold value of the oil temperature.
 5. The control device of a vehicle drive device of claim 1, wherein the oil temperature of the hydraulic oil is detected by an oil temperature sensor and calculated based on the solenoid current of the electromagnetic valve, wherein the oil temperature is normally detected by the oil temperature sensor, and is calculated based on the solenoid current when the oil temperature is not detected by the oil temperature sensor.
 6. The control device of a vehicle drive device of claim 5, wherein a control portion supplied with an oil temperature signal from the oil temperature sensor is separated from a control portion configured to control the oil temperature based on the solenoid current of the electromagnetic valve.
 7. The control device of a vehicle drive device of claim 1, wherein a mechanical oil pump driven by an engine is further included, and wherein the electromagnetic valve oil pump is driven during stop of the engine.
 8. The control device of a vehicle drive device of claim 7, wherein the hydraulic oil discharged from the electromagnetic valve oil pump is supplied to a start clutch of a transmission.
 9. The control device of a vehicle drive device of claim 1, wherein the electromagnetic valve oil pump has an intake oil passage for sucking the hydraulic oil and a discharge oil passage for discharging the hydraulic oil, and wherein a cross-sectional area of the intake oil passage is larger than a cross-sectional area of the discharge oil passage. 